Vitamin D Toxicity Symptoms, Effects, Overdose And More!

Vitamin D, often called the "sunshine vitamin," is essential for bone health, immune function, and metabolic activities. While deficiency is a widespread concern, especially in regions with limited sunlight exposure, recent trends suggest a rise in vitamin D3 overdose and vitamin D toxicity. 

Worldwide, an increased focus on personal health has led to a surge in vitamin D supplementation. However, exceeding recommended doses can lead to vitamin D toxicity symptoms and adverse effects. This is particularly relevant in India, where most of the population experiences vitamin D deficiency. While supplementation is crucial for many, understanding vitamin D toxicity levels is vital to ensure safe and effective practices. 

This blog explores the potential dangers of vitamin D3 overdose. We'll explore the signs and symptoms of vitamin D toxicity, potential health risks, and best practices for maintaining healthy vitamin D levels. Join us as we navigate the world of vitamin D, ensuring you soak up the sunshine's benefits without the risk of an overload. 

Table Of Contents 

1. Understanding Vitamin D And Vitamin D Toxicity 

2. What Are Some Prominent Vitamin D Toxicity Symptoms? 

3. Are There Any Vitamin D Overdose Effects? 

4. Vitamin D Toxicity Treatment and Management 

5. Dietitian’s Recommendation 

6. The Final Say 

7. FAQs 

8. References 

Understanding Vitamin D And Vitamin D Toxicity 

Vitamin D is a vital vitamin and a hormone that the body uses for normal bone development and maintenance. It is a fat-soluble vitamin found in various animal and fortified foods and is also produced endogenously in the human body. Vitamin D3 deficiency symptoms may include fatigue, muscle weakness, bone pain, and frequent infections—more prevalent in India. Now, let’s discuss vitamin D or D3 toxicity.  

Toxicity occurs when foods or supplements are fortified with more vitamin D than intended. In 2015, the FDA announced a voluntary recall of Glades Drugs’ multivitamins due to excessive vitamin D content. In 2016, Danish health authorities recalled a supplement containing vitamin D levels 75 times higher than recommended. Toxicity has occurred in at least 20 children after taking this supplement.    

From 2000 to 2014, 25,397 cases of vitamin D toxicity were reported, and the average number of cases per year between 2000 and 2005 was 196. However, from 2005 to 2011, exposures increased significantly to 1,600. Expressed as a percentage, the average number of new cases per year was 4,535—consumption of vitamin D-fortified milk and vitamin D supplements.  

Now, let’s look at some aspects depicting how vitamin D is essential for the body and a few points regarding vitamin D toxicity:  

1. Vitamin D Is Essential For Bone Health 

Although vitamin D is popularly known to be essential for bone health, its deficiency can cause rickets and osteopenia. An article in PubMed recently elucidated the important role of vitamin D in bone calcification, strength, resilience and coordination of joints. Vitamin D impacts the functioning of the nervous, musculoskeletal, and immune systems. The body converts ingested vitamin D into the “active” form, which helps absorb calcium. 

2. Vitamin D Deficiency Has Reduced 

Due to the availability of supplements and fortified foods, vitamin D deficiency in India has been reduced. A contributing factor could be a growing awareness of the importance of the "sunshine vitamins". Increased public health initiatives promoting supplementation and sun exposure guidelines might also be playing a role.   

3. Hypervitaminosis D Is Rare 

Hypervitaminosis D is not prevalent much and is usually caused by excessive doses of vitamin D due to improper use or incorrect prescription of over-the-counter supplements.  

4. Excess Of Vitamin D Is Toxic 

Vitamin D toxicity occurs when the body has too much vitamin D. It is a rare complication that most often results from taking more vitamin D than prescribed or too much over-the-counter (OTC) medication. Toxicity leads to hypercalcemia and imbalance in the regulation of bone metabolism, resulting in hypercalcemia and associated signs and symptoms. 

5. Prolong Sun Exposure Doesn’t Cause Vitamin D Toxicity 

Long-term sun exposure does not cause vitamin D toxicity because when the skin heats, pre-vitamin D3 is destroyed, and various non-functional forms of vitamin D are formed from heat-activated compounds. Vitamin D toxicity usually occurs only because of taking too many vitamin D supplements or prescription medications.  

Prolonged intake of vitamin D above the recommended upper limit may result in symptoms of toxicity. Excessive vitamin D can cause hypercalcemia (higher than normal calcium levels in the blood), leading to symptoms. Vitamin D toxicity is not life-threatening, but it can be detrimental to your health. In severe cases, problems such as kidney failure, abnormal heartbeat (arrhythmia), unsteady gait (ataxia), and confusion may occur.   

Also Read: Understanding Iron Deficiency: Diet Plan, Recipes, Causes, Symptoms And Treatment  

What Are Some Prominent Vitamin D Toxicity Symptoms? 

Clinical signs and symptoms of vitamin D toxicity result from the effects of hypercalcemia. Often, symptoms can be non-specific and subtle, such as weakness, fatigue, anorexia, and bone pain. Let’s have a look at these symptoms of vitamin D toxicity:  

Also Read: Liver Detox: Which Vitamins Are Good For Liver Repair?  

Are There Any Vitamin D Overdose Effects? 

Vitamin D toxicity usually occurs when taking large doses of vitamin D supplements. Patients who intake high doses of vitamin D are at increased risk of vitamin D toxicity, which can lead to certain diseases or conditions. Here are some prominent effects of vitamin D overdosing: 

1. Hypercalcemia  

A major consequence of vitamin D toxicity is hypercalcemia (calcium buildup in the blood), which can cause nausea and vomiting, weakness, and frequent urination. Treatment includes stopping vitamin D and limiting calcium intake. You may also be prescribed intravenous fluids and corticosteroids or bisphosphonates. 

2. Nephrocalcinosis  

Nephrocalcinosis, characterised by the deposition of calcium salts in the renal parenchyma, can occur due to vitamin D toxicity. Excessive levels of vitamin D can lead to increased calcium absorption in the intestines, resulting in hypercalcemia and subsequent calcium deposition in the kidneys. This deposition can impair renal function and potentially lead to kidney damage if left untreated. In this case, it is advised to seek medical assistance immediately and follow a renal diet meal plan.  

3. Soft Tissue Calcification  

Toxic vitamin D levels (0.075% for D3 and 0.1% for D2) disrupt calcium and phosphate homeostasis. Hypercalcemia results from increased calcium absorption from the gastrointestinal tract and mobilisation of calcium from bone, resulting in extensive soft tissue calcification. 

4. Cardiac Arrhythmias  

Excessive serum vitamin D levels (>150 to 250 ng/mL) have also been associated with potential outcomes, such as cardiac arrhythmias. A significant number of studies have linked vitamin D deficiency to greater risk of developing a cardiac arrhythmia, arterial hypertension, diabetes, and sudden cardiac death. 

5. Bone Loss  

Vitamin D toxicity results in hypercalcemia and an imbalance in the regulation of bone metabolism. As a result, hypercalcemia causes clinical signs and symptoms of toxicity.  

Physical examination of patients with signs of toxicity may reveal loss of skin tone and dry mucous membranes (due to dehydration), changes in mental status, and abdominal tenderness without rebound, stiffness, or tension. Although the physical examination findings may be unremarkable, a high clinical suspicion should be maintained based on historical information. 

Vitamin D Toxicity Treatment and Management 

Your doctor may advise you to stop taking vitamin D supplements immediately. They may also recommend temporarily reducing the amount of calcium in your diet. In some cases, corticosteroids or bisphosphonates can inhibit calcium release from bones.    

Your doctor will frequently monitor your vitamin D levels until they return to normal. Hypervitaminosis D can be prevented by stopping or reducing high-dose vitamin D supplements. There is rarely an acceptable upper limit or maximum daily intake for vitamin D. If there are health risks, the dosage is 4000 IU daily. Side effects have been observed when taking less than 10,000 IU daily for long periods.  Close monitoring is required until vitamin D levels return to normal. Choose vitamin D-deficient foods such leafy greens, whole grains, fruits, and vegetables.